FIG. 1 shows a schematic depiction of a mobile communications network 100 which comprises a first plurality of femtocells 110 and a second plurality of macrocells 120. One macrocell will cover a substantially larger area than a femtocell and thus it will be appreciated that the network 100 may comprise many more femtocells than macrocells. Operators of conventional mobile communications networks deploy femtocells in areas where there are high levels of network use, for example in city centers, shopping malls, transport interchanges. However, there is the possibility that a first organization is operating the plurality of femtocells and that a second organization is operating the plurality of macrocells. In such a scenario, customers of the first organization would have their calls and data sessions routed via a femtocell when they are within the coverage of a femtocell. When the customers were outside of the range of a femtocell then their calls and data sessions would be routed via a macrocell, with a roaming agreement being in place between the first and second organizations.
Thus, it can be seen that the first organization will be motivated for its customers to connect via a femtocell in preference to via a macrocell whenever possible. Firstly, it is likely that users connected via a femtocell will experience a better throughput of data (as typically there will be fewer users in a femtocell than in a macrocell and thus the bandwidth available within a femtocell is likely to be greater than that within a macrocell on a per user basis). Furthermore, there is a commercial driver for the first organization as it will be cheaper to route data via the femtocells as it will not have to pay roaming charges to the second organization for routing data via the macrocells.
U.S. 2012/0015651 discloses a method of determining a network search frequency in the situation where a user terminal moves from a location where there is network coverage to a second location which is outside of the service area provided by the network. U.S. 2011/0124334 discloses a method of cell re-selection when moving from one location to a second location within a defined network.